The present invention relates generally to the art of cutting rumble strips along the shoulder of a highway. Rumble strips, sometimes referred to as “SNAPs” (sonic noise alert patterns) are a series of grooves or depressions formed or cut into the surface of the shoulder of highways, roads, interstates, etc. The grooves provide vibration and therefore noise, when the tires of a vehicle traverse them longitudinally. Road departments use these rumble strips as a safety device longitudinally adjacent the edge of a highway, or along the center line which divides opposing directional traffic flows, are the customarily locations of placement of these rumble strips. They act to alert a driver that his or her vehicle has extended beyond the normal driving surface. Obviously, beyond this normal driving surface many dangerous conditions exist for a vehicle traveling at or near the posted speed limit. These dangers include dirt or gravel shoulders, guardrail barriers, signs, mailboxes, intersecting roadways or driveways, disabled vehicles and oncoming traffic.
Various specifications for the placement and physical dimensions of the individual rumble strips can vary from State to State and even within a particular State. A common size and placement, used for illustration and not limitation, places the individual rumble strips 12 inches apart from the center of one depression to the center of the adjacent depression. The measurements of the individual depressions are generally 7 inches from leading edge to back trailing edge with a depth at the deepest point, of one half inch, and at lateral length across a depression of 16 inches.
It is a difficult, if not impossible, task to form the rumble strips or depressions in the highway surfaces when the surfaces are being created. Moreover, the rumble strips are generally formed in the shoulders of the highways, which are not of the same density and load bearing capacity as the normal highway surface. Forming the depressions in the shoulders would be even more difficult because of the decreased density of the shoulder material and the difficulty in forming depression to cure in the desired shape would be very difficult. For that reason, it is the common practice to pour the shoulder of the highway in the traditional fashion and then follow along afterwards and cut the rumble strips into the shoulder.
Experience with use of rumble strips along the shoulders of highways has demonstrated their tremendous value as a lifesaving tool. If a driver has been driving for a long period of time and is getting fatigued, there is a tendency to nod off or fall asleep and allow the vehicle to drift off of the highway. If the vehicle drifts off to the right, it could go over an embankment and kill or cause sever bodily injury to the driver. With the rumble strips cut into the shoulder, once the vehicle veers off onto the shoulder, the noise created by the tires passing over the rumble strips will immediately awaken the drive and cause him/her to regain control of the vehicle and pull back onto the highway. Likewise, if the driver veers off to the left of the highway, particularly on interstate type highways that are at least two lanes running in each direction with a median in between, the driver could veer into on coming traffic with the potential of resulting head-on collisions that could produce tragic results for many people. Again, the provision of rumble strips on the left hand side of the two lane highway will awaken the driven and cause him to pull back onto the paved highway and avoid these head-on collisions. The value of these rumble strips in terms of their lifesaving effect is no longer open for debate. For that reason, the highway departments of most States are moving rapidly to have all major thoroughfares retrofitted to incorporate rumble strips in the shoulders of those highways.
As would be obvious, there are tens of thousands of miles of highways that need rumble strips cut in their shoulders. The efficiency in cutting the rumble strips is therefore very important. It is also very important to consider the comfort of the person operating the machine to cut the rumble strips and there are potential problems associated with the comfort of the operator in current methods and machinery to carry out those methods under current practices.
More specifically, rumble strip cutters available on the market today generally have a fixed cutting drum. As mentioned above, the cutting drum is usually approximately 16 inches in length and most machines used to drive the rumble strip cutters are at least 4 feet wide. Often, the cutting drum is mounted in the middle of the machine, leaving the drum at least 16 inches from the outside edge of both sides of the machine. These physical arrangements of the cutting drum within the machine make it very difficult to cut rumble strips at places on the road where the shoulder is very narrow, either because there is a drop off of the topography, or other obstacles such as bridge abutments, pylons, guardrails and the like. Other machines are configured so that the rumble strip cutting drum is adjacent one side of the machine so as to enable the machine to make close cuts in situations where the shoulder of the road is very narrow for any of the reasons as indicated above. However, historically, the cutting drums of these machines are always fixed in place or, at a minimum, cannot be conveniently moved from one side of the machine to the other. Thus, on an interstate type highway where there are four lanes of traffic, two in each direction, if the drum is mounted to the right side of the machine, when cutting the rumble strips in the right shoulder, the machine can move in the direction of flow of the traffic and cut rumble strips on narrow shoulders. However, when cutting rumbles in the left shoulder, the machine must either be driven into the direction of traffic, creating major safety hazards for the operator, or the machine can function properly only in areas that have very wide shoulders. Even if the machine could be operated moving against the direction, traffic control becomes a major problem.
What is needed then is a rumble strip cutting machine that has a drum that can be conveniently shifted from one side of the machine to the other and a machine that will enable a method of cutting rumble strips close to obstructions on narrow shoulders while always driving the machine in the direction of moving traffic on the highway. Such a machine and method is not currently available in the prior art.